migration/colo.c

   1 /*
   2  * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
   3  * (a.k.a. Fault Tolerance or Continuous Replication)
   4  *
   5  * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
   6  * Copyright (c) 2016 FUJITSU LIMITED
   7  * Copyright (c) 2016 Intel Corporation
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or
  10  * later.  See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "sysemu/sysemu.h"
  15 #include "qapi/error.h"
  16 #include "qapi/qapi-commands-migration.h"
  17 #include "migration.h"
  18 #include "qemu-file.h"
  19 #include "savevm.h"
  20 #include "migration/colo.h"
  21 #include "block.h"
  22 #include "io/channel-buffer.h"
  23 #include "trace.h"
  24 #include "qemu/error-report.h"
  25 #include "qemu/main-loop.h"
  26 #include "qemu/rcu.h"
  27 #include "migration/failover.h"
  28 #include "migration/ram.h"
  29 #ifdef CONFIG_REPLICATION
  30 #include "block/replication.h"
  31 #endif
  32 #include "net/colo-compare.h"
  33 #include "net/colo.h"
  34 #include "block/block.h"
  35 #include "qapi/qapi-events-migration.h"
  36 #include "sysemu/cpus.h"
  37 #include "sysemu/runstate.h"
  38 #include "net/filter.h"
  39 #include "options.h"
  40
  41 static bool vmstate_loading;
  42 static Notifier packets_compare_notifier;
  43
  44 /* User need to know colo mode after COLO failover */
  45 static COLOMode last_colo_mode;
  46
  47 #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
  48
  49 bool migration_in_colo_state(void)
  50 {
  51     MigrationState *s = migrate_get_current();
  52
  53     return (s->state == MIGRATION_STATUS_COLO);
  54 }
  55
  56 bool migration_incoming_in_colo_state(void)
  57 {
  58     MigrationIncomingState *mis = migration_incoming_get_current();
  59
  60     return mis && (mis->state == MIGRATION_STATUS_COLO);
  61 }
  62
  63 static bool colo_runstate_is_stopped(void)
  64 {
  65     return runstate_check(RUN_STATE_COLO) || !runstate_is_running();
  66 }
  67
  68 static void secondary_vm_do_failover(void)
  69 {
  70 /* COLO needs enable block-replication */
  71 #ifdef CONFIG_REPLICATION
  72     int old_state;
  73     MigrationIncomingState *mis = migration_incoming_get_current();
  74     Error *local_err = NULL;
  75
  76     /* Can not do failover during the process of VM's loading VMstate, Or
  77      * it will break the secondary VM.
  78      */
  79     if (vmstate_loading) {
  80         old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
  81                         FAILOVER_STATUS_RELAUNCH);
  82         if (old_state != FAILOVER_STATUS_ACTIVE) {
  83             error_report("Unknown error while do failover for secondary VM,"
  84                          "old_state: %s", FailoverStatus_str(old_state));
  85         }
  86         return;
  87     }
  88
  89     migrate_set_state(&mis->state, MIGRATION_STATUS_COLO,
  90                       MIGRATION_STATUS_COMPLETED);
  91
  92     replication_stop_all(true, &local_err);
  93     if (local_err) {
  94         error_report_err(local_err);
  95         local_err = NULL;
  96     }
  97
  98     /* Notify all filters of all NIC to do checkpoint */
  99     colo_notify_filters_event(COLO_EVENT_FAILOVER, &local_err);
 100     if (local_err) {
 101         error_report_err(local_err);
 102     }
 103
 104     if (!autostart) {
 105         error_report("\"-S\" qemu option will be ignored in secondary side");
 106         /* recover runstate to normal migration finish state */
 107         autostart = true;
 108     }
 109     /*
 110      * Make sure COLO incoming thread not block in recv or send,
 111      * If mis->from_src_file and mis->to_src_file use the same fd,
 112      * The second shutdown() will return -1, we ignore this value,
 113      * It is harmless.
 114      */
 115     if (mis->from_src_file) {
 116         qemu_file_shutdown(mis->from_src_file);
 117     }
 118     if (mis->to_src_file) {
 119         qemu_file_shutdown(mis->to_src_file);
 120     }
 121
 122     old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
 123                                    FAILOVER_STATUS_COMPLETED);
 124     if (old_state != FAILOVER_STATUS_ACTIVE) {
 125         error_report("Incorrect state (%s) while doing failover for "
 126                      "secondary VM", FailoverStatus_str(old_state));
 127         return;
 128     }
 129     /* Notify COLO incoming thread that failover work is finished */
 130     qemu_sem_post(&mis->colo_incoming_sem);
 131
 132     /* For Secondary VM, jump to incoming co */
 133     if (mis->migration_incoming_co) {
 134         qemu_coroutine_enter(mis->migration_incoming_co);
 135     }
 136 #else
 137     abort();
 138 #endif
 139 }
 140
 141 static void primary_vm_do_failover(void)
 142 {
 143 #ifdef CONFIG_REPLICATION
 144     MigrationState *s = migrate_get_current();
 145     int old_state;
 146     Error *local_err = NULL;
 147
 148     migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
 149                       MIGRATION_STATUS_COMPLETED);
 150     /*
 151      * kick COLO thread which might wait at
 152      * qemu_sem_wait(&s->colo_checkpoint_sem).
 153      */
 154     colo_checkpoint_notify(s);
 155
 156     /*
 157      * Wake up COLO thread which may blocked in recv() or send(),
 158      * The s->rp_state.from_dst_file and s->to_dst_file may use the
 159      * same fd, but we still shutdown the fd for twice, it is harmless.
 160      */
 161     if (s->to_dst_file) {
 162         qemu_file_shutdown(s->to_dst_file);
 163     }
 164     if (s->rp_state.from_dst_file) {
 165         qemu_file_shutdown(s->rp_state.from_dst_file);
 166     }
 167
 168     old_state = failover_set_state(FAILOVER_STATUS_ACTIVE,
 169                                    FAILOVER_STATUS_COMPLETED);
 170     if (old_state != FAILOVER_STATUS_ACTIVE) {
 171         error_report("Incorrect state (%s) while doing failover for Primary VM",
 172                      FailoverStatus_str(old_state));
 173         return;
 174     }
 175
 176     replication_stop_all(true, &local_err);
 177     if (local_err) {
 178         error_report_err(local_err);
 179         local_err = NULL;
 180     }
 181
 182     /* Notify COLO thread that failover work is finished */
 183     qemu_sem_post(&s->colo_exit_sem);
 184 #else
 185     abort();
 186 #endif
 187 }
 188
 189 COLOMode get_colo_mode(void)
 190 {
 191     if (migration_in_colo_state()) {
 192         return COLO_MODE_PRIMARY;
 193     } else if (migration_incoming_in_colo_state()) {
 194         return COLO_MODE_SECONDARY;
 195     } else {
 196         return COLO_MODE_NONE;
 197     }
 198 }
 199
 200 void colo_do_failover(void)
 201 {
 202     /* Make sure VM stopped while failover happened. */
 203     if (!colo_runstate_is_stopped()) {
 204         vm_stop_force_state(RUN_STATE_COLO);
 205     }
 206
 207     switch (last_colo_mode = get_colo_mode()) {
 208     case COLO_MODE_PRIMARY:
 209         primary_vm_do_failover();
 210         break;
 211     case COLO_MODE_SECONDARY:
 212         secondary_vm_do_failover();
 213         break;
 214     default:
 215         error_report("colo_do_failover failed because the colo mode"
 216                      " could not be obtained");
 217     }
 218 }
 219
 220 #ifdef CONFIG_REPLICATION
 221 void qmp_xen_set_replication(bool enable, bool primary,
 222                              bool has_failover, bool failover,
 223                              Error **errp)
 224 {
 225     ReplicationMode mode = primary ?
 226                            REPLICATION_MODE_PRIMARY :
 227                            REPLICATION_MODE_SECONDARY;
 228
 229     if (has_failover && enable) {
 230         error_setg(errp, "Parameter 'failover' is only for"
 231                    " stopping replication");
 232         return;
 233     }
 234
 235     if (enable) {
 236         replication_start_all(mode, errp);
 237     } else {
 238         if (!has_failover) {
 239             failover = NULL;
 240         }
 241         replication_stop_all(failover, failover ? NULL : errp);
 242     }
 243 }
 244
 245 ReplicationStatus *qmp_query_xen_replication_status(Error **errp)
 246 {
 247     Error *err = NULL;
 248     ReplicationStatus *s = g_new0(ReplicationStatus, 1);
 249
 250     replication_get_error_all(&err);
 251     if (err) {
 252         s->error = true;
 253         s->desc = g_strdup(error_get_pretty(err));
 254     } else {
 255         s->error = false;
 256     }
 257
 258     error_free(err);
 259     return s;
 260 }
 261
 262 void qmp_xen_colo_do_checkpoint(Error **errp)
 263 {
 264     Error *err = NULL;
 265
 266     replication_do_checkpoint_all(&err);
 267     if (err) {
 268         error_propagate(errp, err);
 269         return;
 270     }
 271     /* Notify all filters of all NIC to do checkpoint */
 272     colo_notify_filters_event(COLO_EVENT_CHECKPOINT, errp);
 273 }
 274 #endif
 275
 276 COLOStatus *qmp_query_colo_status(Error **errp)
 277 {
 278     COLOStatus *s = g_new0(COLOStatus, 1);
 279
 280     s->mode = get_colo_mode();
 281     s->last_mode = last_colo_mode;
 282
 283     switch (failover_get_state()) {
 284     case FAILOVER_STATUS_NONE:
 285         s->reason = COLO_EXIT_REASON_NONE;
 286         break;
 287     case FAILOVER_STATUS_COMPLETED:
 288         s->reason = COLO_EXIT_REASON_REQUEST;
 289         break;
 290     default:
 291         if (migration_in_colo_state()) {
 292             s->reason = COLO_EXIT_REASON_PROCESSING;
 293         } else {
 294             s->reason = COLO_EXIT_REASON_ERROR;
 295         }
 296     }
 297
 298     return s;
 299 }
 300
 301 static void colo_send_message(QEMUFile *f, COLOMessage msg,
 302                               Error **errp)
 303 {
 304     int ret;
 305
 306     if (msg >= COLO_MESSAGE__MAX) {
 307         error_setg(errp, "%s: Invalid message", __func__);
 308         return;
 309     }
 310     qemu_put_be32(f, msg);
 311     qemu_fflush(f);
 312
 313     ret = qemu_file_get_error(f);
 314     if (ret < 0) {
 315         error_setg_errno(errp, -ret, "Can't send COLO message");
 316     }
 317     trace_colo_send_message(COLOMessage_str(msg));
 318 }
 319
 320 static void colo_send_message_value(QEMUFile *f, COLOMessage msg,
 321                                     uint64_t value, Error **errp)
 322 {
 323     Error *local_err = NULL;
 324     int ret;
 325
 326     colo_send_message(f, msg, &local_err);
 327     if (local_err) {
 328         error_propagate(errp, local_err);
 329         return;
 330     }
 331     qemu_put_be64(f, value);
 332     qemu_fflush(f);
 333
 334     ret = qemu_file_get_error(f);
 335     if (ret < 0) {
 336         error_setg_errno(errp, -ret, "Failed to send value for message:%s",
 337                          COLOMessage_str(msg));
 338     }
 339 }
 340
 341 static COLOMessage colo_receive_message(QEMUFile *f, Error **errp)
 342 {
 343     COLOMessage msg;
 344     int ret;
 345
 346     msg = qemu_get_be32(f);
 347     ret = qemu_file_get_error(f);
 348     if (ret < 0) {
 349         error_setg_errno(errp, -ret, "Can't receive COLO message");
 350         return msg;
 351     }
 352     if (msg >= COLO_MESSAGE__MAX) {
 353         error_setg(errp, "%s: Invalid message", __func__);
 354         return msg;
 355     }
 356     trace_colo_receive_message(COLOMessage_str(msg));
 357     return msg;
 358 }
 359
 360 static void colo_receive_check_message(QEMUFile *f, COLOMessage expect_msg,
 361                                        Error **errp)
 362 {
 363     COLOMessage msg;
 364     Error *local_err = NULL;
 365
 366     msg = colo_receive_message(f, &local_err);
 367     if (local_err) {
 368         error_propagate(errp, local_err);
 369         return;
 370     }
 371     if (msg != expect_msg) {
 372         error_setg(errp, "Unexpected COLO message %d, expected %d",
 373                           msg, expect_msg);
 374     }
 375 }
 376
 377 static uint64_t colo_receive_message_value(QEMUFile *f, uint32_t expect_msg,
 378                                            Error **errp)
 379 {
 380     Error *local_err = NULL;
 381     uint64_t value;
 382     int ret;
 383
 384     colo_receive_check_message(f, expect_msg, &local_err);
 385     if (local_err) {
 386         error_propagate(errp, local_err);
 387         return 0;
 388     }
 389
 390     value = qemu_get_be64(f);
 391     ret = qemu_file_get_error(f);
 392     if (ret < 0) {
 393         error_setg_errno(errp, -ret, "Failed to get value for COLO message: %s",
 394                          COLOMessage_str(expect_msg));
 395     }
 396     return value;
 397 }
 398
 399 static int colo_do_checkpoint_transaction(MigrationState *s,
 400                                           QIOChannelBuffer *bioc,
 401                                           QEMUFile *fb)
 402 {
 403     Error *local_err = NULL;
 404     int ret = -1;
 405
 406     colo_send_message(s->to_dst_file, COLO_MESSAGE_CHECKPOINT_REQUEST,
 407                       &local_err);
 408     if (local_err) {
 409         goto out;
 410     }
 411
 412     colo_receive_check_message(s->rp_state.from_dst_file,
 413                     COLO_MESSAGE_CHECKPOINT_REPLY, &local_err);
 414     if (local_err) {
 415         goto out;
 416     }
 417     /* Reset channel-buffer directly */
 418     qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
 419     bioc->usage = 0;
 420
 421     qemu_mutex_lock_iothread();
 422     if (failover_get_state() != FAILOVER_STATUS_NONE) {
 423         qemu_mutex_unlock_iothread();
 424         goto out;
 425     }
 426     vm_stop_force_state(RUN_STATE_COLO);
 427     qemu_mutex_unlock_iothread();
 428     trace_colo_vm_state_change("run", "stop");
 429     /*
 430      * Failover request bh could be called after vm_stop_force_state(),
 431      * So we need check failover_request_is_active() again.
 432      */
 433     if (failover_get_state() != FAILOVER_STATUS_NONE) {
 434         goto out;
 435     }
 436     qemu_mutex_lock_iothread();
 437
 438 #ifdef CONFIG_REPLICATION
 439     replication_do_checkpoint_all(&local_err);
 440     if (local_err) {
 441         qemu_mutex_unlock_iothread();
 442         goto out;
 443     }
 444 #else
 445         abort();
 446 #endif
 447
 448     colo_send_message(s->to_dst_file, COLO_MESSAGE_VMSTATE_SEND, &local_err);
 449     if (local_err) {
 450         qemu_mutex_unlock_iothread();
 451         goto out;
 452     }
 453     /* Note: device state is saved into buffer */
 454     ret = qemu_save_device_state(fb);
 455
 456     qemu_mutex_unlock_iothread();
 457     if (ret < 0) {
 458         goto out;
 459     }
 460
 461     if (migrate_auto_converge()) {
 462         mig_throttle_counter_reset();
 463     }
 464     /*
 465      * Only save VM's live state, which not including device state.
 466      * TODO: We may need a timeout mechanism to prevent COLO process
 467      * to be blocked here.
 468      */
 469     qemu_savevm_live_state(s->to_dst_file);
 470
 471     qemu_fflush(fb);
 472
 473     /*
 474      * We need the size of the VMstate data in Secondary side,
 475      * With which we can decide how much data should be read.
 476      */
 477     colo_send_message_value(s->to_dst_file, COLO_MESSAGE_VMSTATE_SIZE,
 478                             bioc->usage, &local_err);
 479     if (local_err) {
 480         goto out;
 481     }
 482
 483     qemu_put_buffer(s->to_dst_file, bioc->data, bioc->usage);
 484     qemu_fflush(s->to_dst_file);
 485     ret = qemu_file_get_error(s->to_dst_file);
 486     if (ret < 0) {
 487         goto out;
 488     }
 489
 490     colo_receive_check_message(s->rp_state.from_dst_file,
 491                        COLO_MESSAGE_VMSTATE_RECEIVED, &local_err);
 492     if (local_err) {
 493         goto out;
 494     }
 495
 496     qemu_event_reset(&s->colo_checkpoint_event);
 497     colo_notify_compares_event(NULL, COLO_EVENT_CHECKPOINT, &local_err);
 498     if (local_err) {
 499         goto out;
 500     }
 501
 502     colo_receive_check_message(s->rp_state.from_dst_file,
 503                        COLO_MESSAGE_VMSTATE_LOADED, &local_err);
 504     if (local_err) {
 505         goto out;
 506     }
 507
 508     ret = 0;
 509
 510     qemu_mutex_lock_iothread();
 511     vm_start();
 512     qemu_mutex_unlock_iothread();
 513     trace_colo_vm_state_change("stop", "run");
 514
 515 out:
 516     if (local_err) {
 517         error_report_err(local_err);
 518     }
 519     return ret;
 520 }
 521
 522 static void colo_compare_notify_checkpoint(Notifier *notifier, void *data)
 523 {
 524     colo_checkpoint_notify(data);
 525 }
 526
 527 static void colo_process_checkpoint(MigrationState *s)
 528 {
 529     QIOChannelBuffer *bioc;
 530     QEMUFile *fb = NULL;
 531     Error *local_err = NULL;
 532     int ret;
 533
 534     if (get_colo_mode() != COLO_MODE_PRIMARY) {
 535         error_report("COLO mode must be COLO_MODE_PRIMARY");
 536         return;
 537     }
 538
 539     failover_init_state();
 540
 541     s->rp_state.from_dst_file = qemu_file_get_return_path(s->to_dst_file);
 542     if (!s->rp_state.from_dst_file) {
 543         error_report("Open QEMUFile from_dst_file failed");
 544         goto out;
 545     }
 546
 547     packets_compare_notifier.notify = colo_compare_notify_checkpoint;
 548     colo_compare_register_notifier(&packets_compare_notifier);
 549
 550     /*
 551      * Wait for Secondary finish loading VM states and enter COLO
 552      * restore.
 553      */
 554     colo_receive_check_message(s->rp_state.from_dst_file,
 555                        COLO_MESSAGE_CHECKPOINT_READY, &local_err);
 556     if (local_err) {
 557         goto out;
 558     }
 559     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
 560     fb = qemu_file_new_output(QIO_CHANNEL(bioc));
 561     object_unref(OBJECT(bioc));
 562
 563     qemu_mutex_lock_iothread();
 564 #ifdef CONFIG_REPLICATION
 565     replication_start_all(REPLICATION_MODE_PRIMARY, &local_err);
 566     if (local_err) {
 567         qemu_mutex_unlock_iothread();
 568         goto out;
 569     }
 570 #else
 571         abort();
 572 #endif
 573
 574     vm_start();
 575     qemu_mutex_unlock_iothread();
 576     trace_colo_vm_state_change("stop", "run");
 577
 578     timer_mod(s->colo_delay_timer, qemu_clock_get_ms(QEMU_CLOCK_HOST) +
 579               migrate_checkpoint_delay());
 580
 581     while (s->state == MIGRATION_STATUS_COLO) {
 582         if (failover_get_state() != FAILOVER_STATUS_NONE) {
 583             error_report("failover request");
 584             goto out;
 585         }
 586
 587         qemu_event_wait(&s->colo_checkpoint_event);
 588
 589         if (s->state != MIGRATION_STATUS_COLO) {
 590             goto out;
 591         }
 592         ret = colo_do_checkpoint_transaction(s, bioc, fb);
 593         if (ret < 0) {
 594             goto out;
 595         }
 596     }
 597
 598 out:
 599     /* Throw the unreported error message after exited from loop */
 600     if (local_err) {
 601         error_report_err(local_err);
 602     }
 603
 604     if (fb) {
 605         qemu_fclose(fb);
 606     }
 607
 608     /*
 609      * There are only two reasons we can get here, some error happened
 610      * or the user triggered failover.
 611      */
 612     switch (failover_get_state()) {
 613     case FAILOVER_STATUS_COMPLETED:
 614         qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
 615                                   COLO_EXIT_REASON_REQUEST);
 616         break;
 617     default:
 618         qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
 619                                   COLO_EXIT_REASON_ERROR);
 620     }
 621
 622     /* Hope this not to be too long to wait here */
 623     qemu_sem_wait(&s->colo_exit_sem);
 624     qemu_sem_destroy(&s->colo_exit_sem);
 625
 626     /*
 627      * It is safe to unregister notifier after failover finished.
 628      * Besides, colo_delay_timer and colo_checkpoint_sem can't be
 629      * released before unregister notifier, or there will be use-after-free
 630      * error.
 631      */
 632     colo_compare_unregister_notifier(&packets_compare_notifier);
 633     timer_free(s->colo_delay_timer);
 634     qemu_event_destroy(&s->colo_checkpoint_event);
 635
 636     /*
 637      * Must be called after failover BH is completed,
 638      * Or the failover BH may shutdown the wrong fd that
 639      * re-used by other threads after we release here.
 640      */
 641     if (s->rp_state.from_dst_file) {
 642         qemu_fclose(s->rp_state.from_dst_file);
 643         s->rp_state.from_dst_file = NULL;
 644     }
 645 }
 646
 647 void colo_checkpoint_notify(void *opaque)
 648 {
 649     MigrationState *s = opaque;
 650     int64_t next_notify_time;
 651
 652     qemu_event_set(&s->colo_checkpoint_event);
 653     s->colo_checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 654     next_notify_time = s->colo_checkpoint_time + migrate_checkpoint_delay();
 655     timer_mod(s->colo_delay_timer, next_notify_time);
 656 }
 657
 658 void migrate_start_colo_process(MigrationState *s)
 659 {
 660     qemu_mutex_unlock_iothread();
 661     qemu_event_init(&s->colo_checkpoint_event, false);
 662     s->colo_delay_timer =  timer_new_ms(QEMU_CLOCK_HOST,
 663                                 colo_checkpoint_notify, s);
 664
 665     qemu_sem_init(&s->colo_exit_sem, 0);
 666     colo_process_checkpoint(s);
 667     qemu_mutex_lock_iothread();
 668 }
 669
 670 static void colo_incoming_process_checkpoint(MigrationIncomingState *mis,
 671                       QEMUFile *fb, QIOChannelBuffer *bioc, Error **errp)
 672 {
 673     uint64_t total_size;
 674     uint64_t value;
 675     Error *local_err = NULL;
 676     int ret;
 677
 678     qemu_mutex_lock_iothread();
 679     vm_stop_force_state(RUN_STATE_COLO);
 680     qemu_mutex_unlock_iothread();
 681     trace_colo_vm_state_change("run", "stop");
 682
 683     /* FIXME: This is unnecessary for periodic checkpoint mode */
 684     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_REPLY,
 685                  &local_err);
 686     if (local_err) {
 687         error_propagate(errp, local_err);
 688         return;
 689     }
 690
 691     colo_receive_check_message(mis->from_src_file,
 692                        COLO_MESSAGE_VMSTATE_SEND, &local_err);
 693     if (local_err) {
 694         error_propagate(errp, local_err);
 695         return;
 696     }
 697
 698     qemu_mutex_lock_iothread();
 699     cpu_synchronize_all_states();
 700     ret = qemu_loadvm_state_main(mis->from_src_file, mis);
 701     qemu_mutex_unlock_iothread();
 702
 703     if (ret < 0) {
 704         error_setg(errp, "Load VM's live state (ram) error");
 705         return;
 706     }
 707
 708     value = colo_receive_message_value(mis->from_src_file,
 709                              COLO_MESSAGE_VMSTATE_SIZE, &local_err);
 710     if (local_err) {
 711         error_propagate(errp, local_err);
 712         return;
 713     }
 714
 715     /*
 716      * Read VM device state data into channel buffer,
 717      * It's better to re-use the memory allocated.
 718      * Here we need to handle the channel buffer directly.
 719      */
 720     if (value > bioc->capacity) {
 721         bioc->capacity = value;
 722         bioc->data = g_realloc(bioc->data, bioc->capacity);
 723     }
 724     total_size = qemu_get_buffer(mis->from_src_file, bioc->data, value);
 725     if (total_size != value) {
 726         error_setg(errp, "Got %" PRIu64 " VMState data, less than expected"
 727                     " %" PRIu64, total_size, value);
 728         return;
 729     }
 730     bioc->usage = total_size;
 731     qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
 732
 733     colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_RECEIVED,
 734                  &local_err);
 735     if (local_err) {
 736         error_propagate(errp, local_err);
 737         return;
 738     }
 739
 740     qemu_mutex_lock_iothread();
 741     vmstate_loading = true;
 742     colo_flush_ram_cache();
 743     ret = qemu_load_device_state(fb);
 744     if (ret < 0) {
 745         error_setg(errp, "COLO: load device state failed");
 746         vmstate_loading = false;
 747         qemu_mutex_unlock_iothread();
 748         return;
 749     }
 750
 751 #ifdef CONFIG_REPLICATION
 752     replication_get_error_all(&local_err);
 753     if (local_err) {
 754         error_propagate(errp, local_err);
 755         vmstate_loading = false;
 756         qemu_mutex_unlock_iothread();
 757         return;
 758     }
 759
 760     /* discard colo disk buffer */
 761     replication_do_checkpoint_all(&local_err);
 762     if (local_err) {
 763         error_propagate(errp, local_err);
 764         vmstate_loading = false;
 765         qemu_mutex_unlock_iothread();
 766         return;
 767     }
 768 #else
 769     abort();
 770 #endif
 771     /* Notify all filters of all NIC to do checkpoint */
 772     colo_notify_filters_event(COLO_EVENT_CHECKPOINT, &local_err);
 773
 774     if (local_err) {
 775         error_propagate(errp, local_err);
 776         vmstate_loading = false;
 777         qemu_mutex_unlock_iothread();
 778         return;
 779     }
 780
 781     vmstate_loading = false;
 782     vm_start();
 783     qemu_mutex_unlock_iothread();
 784     trace_colo_vm_state_change("stop", "run");
 785
 786     if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
 787         return;
 788     }
 789
 790     colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_LOADED,
 791                  &local_err);
 792     error_propagate(errp, local_err);
 793 }
 794
 795 static void colo_wait_handle_message(MigrationIncomingState *mis,
 796                 QEMUFile *fb, QIOChannelBuffer *bioc, Error **errp)
 797 {
 798     COLOMessage msg;
 799     Error *local_err = NULL;
 800
 801     msg = colo_receive_message(mis->from_src_file, &local_err);
 802     if (local_err) {
 803         error_propagate(errp, local_err);
 804         return;
 805     }
 806
 807     switch (msg) {
 808     case COLO_MESSAGE_CHECKPOINT_REQUEST:
 809         colo_incoming_process_checkpoint(mis, fb, bioc, errp);
 810         break;
 811     default:
 812         error_setg(errp, "Got unknown COLO message: %d", msg);
 813         break;
 814     }
 815 }
 816
 817 void colo_shutdown(void)
 818 {
 819     MigrationIncomingState *mis = NULL;
 820     MigrationState *s = NULL;
 821
 822     switch (get_colo_mode()) {
 823     case COLO_MODE_PRIMARY:
 824         s = migrate_get_current();
 825         qemu_event_set(&s->colo_checkpoint_event);
 826         qemu_sem_post(&s->colo_exit_sem);
 827         break;
 828     case COLO_MODE_SECONDARY:
 829         mis = migration_incoming_get_current();
 830         qemu_sem_post(&mis->colo_incoming_sem);
 831         break;
 832     default:
 833         break;
 834     }
 835 }
 836
 837 void *colo_process_incoming_thread(void *opaque)
 838 {
 839     MigrationIncomingState *mis = opaque;
 840     QEMUFile *fb = NULL;
 841     QIOChannelBuffer *bioc = NULL; /* Cache incoming device state */
 842     Error *local_err = NULL;
 843
 844     rcu_register_thread();
 845     qemu_sem_init(&mis->colo_incoming_sem, 0);
 846
 847     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
 848                       MIGRATION_STATUS_COLO);
 849
 850     if (get_colo_mode() != COLO_MODE_SECONDARY) {
 851         error_report("COLO mode must be COLO_MODE_SECONDARY");
 852         return NULL;
 853     }
 854
 855     failover_init_state();
 856
 857     mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
 858     if (!mis->to_src_file) {
 859         error_report("COLO incoming thread: Open QEMUFile to_src_file failed");
 860         goto out;
 861     }
 862     /*
 863      * Note: the communication between Primary side and Secondary side
 864      * should be sequential, we set the fd to unblocked in migration incoming
 865      * coroutine, and here we are in the COLO incoming thread, so it is ok to
 866      * set the fd back to blocked.
 867      */
 868     qemu_file_set_blocking(mis->from_src_file, true);
 869
 870     colo_incoming_start_dirty_log();
 871
 872     bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE);
 873     fb = qemu_file_new_input(QIO_CHANNEL(bioc));
 874     object_unref(OBJECT(bioc));
 875
 876     qemu_mutex_lock_iothread();
 877 #ifdef CONFIG_REPLICATION
 878     replication_start_all(REPLICATION_MODE_SECONDARY, &local_err);
 879     if (local_err) {
 880         qemu_mutex_unlock_iothread();
 881         goto out;
 882     }
 883 #else
 884         abort();
 885 #endif
 886     vm_start();
 887     qemu_mutex_unlock_iothread();
 888     trace_colo_vm_state_change("stop", "run");
 889
 890     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_READY,
 891                       &local_err);
 892     if (local_err) {
 893         goto out;
 894     }
 895
 896     while (mis->state == MIGRATION_STATUS_COLO) {
 897         colo_wait_handle_message(mis, fb, bioc, &local_err);
 898         if (local_err) {
 899             error_report_err(local_err);
 900             break;
 901         }
 902
 903         if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
 904             failover_set_state(FAILOVER_STATUS_RELAUNCH,
 905                             FAILOVER_STATUS_NONE);
 906             failover_request_active(NULL);
 907             break;
 908         }
 909
 910         if (failover_get_state() != FAILOVER_STATUS_NONE) {
 911             error_report("failover request");
 912             break;
 913         }
 914     }
 915
 916 out:
 917     /*
 918      * There are only two reasons we can get here, some error happened
 919      * or the user triggered failover.
 920      */
 921     switch (failover_get_state()) {
 922     case FAILOVER_STATUS_COMPLETED:
 923         qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
 924                                   COLO_EXIT_REASON_REQUEST);
 925         break;
 926     default:
 927         qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
 928                                   COLO_EXIT_REASON_ERROR);
 929     }
 930
 931     if (fb) {
 932         qemu_fclose(fb);
 933     }
 934
 935     /* Hope this not to be too long to loop here */
 936     qemu_sem_wait(&mis->colo_incoming_sem);
 937     qemu_sem_destroy(&mis->colo_incoming_sem);
 938
 939     rcu_unregister_thread();
 940     return NULL;
 941 }